Protective device for a hand machine tool

ABSTRACT

The invention is based on a guard device ( 33 ) for a power tool, in particular for a sanding power tool, having a protective cover ( 40 ) that is provided to at least partially encompass a disk-shaped, rotating tool, and having a dust removal tube ( 52 ), the longitudinal axis of which is located at an angle of up to 80° to the axis of rotation of the tool. 
     It is proposed that part of the dust removal tube ( 52 ) passes through the plane of a flat side of the tool.

BACKGROUND OF THE INVENTION

The invention is based on a guard device for a power tool, in particularfor a sanding power tool.

Guard devices for power tools, in particular for angle grinders, areknown, the protective covers of which offer a certain level ofprotection during sanding work, but do not support sufficient dustremoval despite the powerful external vacuum cleaners typically used.Additionally, the typical, radial routing of the suction tube makeshandling the power tool difficult because the suction tube protrudesradially.

SUMMARY OF THE INVENTION

The invention is based on a guard device for a power tool, in particularfor a sanding power tool, having a protective cover that is provided toat least partially encompass a disk-shaped, rotating tool, and having adust removal tube, the longitudinal axis of which is located at an angleof up to 80° to the axis of rotation of the tool.

It is proposed that part of the dust removal tube passes through theplane of a flat side of the tool.

Good handling of the power tool is obtained by means of the slantedrouting of the dust removal tube, whereby, simultaneously, particularlyeffective dust removal is obtained by means of the design of the dustremoval tube, so that, in most cases, neither an internal ventilator noran external vacuum cleaner are needed. This is essentially achieved inthat at least some of particles or sanding dust cast off by the tool arethrown directly into the interior of the dust removal tube and do notfirst have to find their way from the inside of the protective cover tothe opening of the dust removal tube. Additionally, the part of the dustremoval tube that passes through the plane of a flat side of the toolusually forms a bent surface that is a conducting surface, and directsthe conveying air stream produced by the rapid rotation of the tool frominside the protective cover into the dust removal tube with only minimalenergy loss.

The dust removal tube located at a slant to the axis of rotation of thetool makes good dust removal possible without external vacuuming due tothe defined natural motion of the dust particles, and allows goodfreedom of motion while working. The sanding dust is captured andremoved particularly well due to the over-the-corner location of thedust removal tube immediately next to the site where the tools exits awork piece surface.

A particularly advantageous redirection of the conveying air and theparticles is obtained in that the tool—with its radially outermostregion—passes through an opening in the dust removal tube. The peripheryof the disk-shaped tool is therefore at least partially encompassed by apart of the dust removal tool. As a result, conveying air and particleson both sides of the plane of rotation of the tool are guided directlyinto the dust removal tool. The opening can be designed as a slot, forexample, into which the periphery of the tool enters. The geometery,e.g., the bend, of the part of the dust removal tube that forms theopening can differ from the geometry of the adjacent part of the dustremoval tube. For example, the dust removal tube—in the part of it thatencompasses the tool—can be bent upward or downward, or it can haveanother form appearing favorable to one skilled in the art.

Advantageously, the part of the dust removal tube that passes throughthe plane of the flat side of the tool is situated so that sanding dustdrawn off of a work piece by the tool is set into a rotational motion inthe dust removal tube. When the conveying air stream with the sandingdust meets this part of the dust removal tube, the air and sanding dustare further directed into the dust removal tube in such a fashion thatthey execute a cyclone-like vortex motion in the dust removal tube. Theconveying air and dust stream set into rotational motion in this fashioncan have sufficient kinetic energy to exit the dust removal tube on itsside furthest from the tool under its own power.

Due to the fact that the dust removal tube tapers toward its mouthpointing toward the tool, the natural motion of the dust particles andthe blow-off effect are markedly improved by means of the air movementcreated by the rotating sanding disk. The conveying air stream flowsrapidly in the axial direction of the dust removal tube through theconstriction in the mouth of the dust removal tube and therefore leavesthe inner space of the protective cover with great speed. If the airalso executes a rotating motion in the dust removal tube, the air streamdevelops a suction effect due to the widening of the dust removal tubein the direction away from the protective cover, which said suctioneffect helps the air to exit the protective cover and enter the dustremoval tube.

In an advantageous embodiment of the invention, the guard devicecomprises a fastening device to fasten the protective cover to the powertool, whereby the dust removal tube is moveably supported relative tothe fastening device. In this fashion, the dust removal tube can be heldmoveably in relation to the tool and, therefore, independent of thedepth of penetration of the tool in a work piece with a constant, e.g.,very small clearance. As a result, the mouth of the dust removal toolcan be positioned very close to the site where the particles leave thework piece, by way of which good removal of the particles is obtained.

Advantageously, the dust removal tube is fastened to the protectivecover. In this fashion, it is positioned in a way that is stable andeasy to produce.

Particularly good sanding dust removal can be achieved when theprotective cover is intended—in a state in which it lies on a flat workpiece in the operating position—to encompass the tool together with thework piece to an extent that does not depend on the depth of penetrationof the tool in the work piece. The work piece can be encompassedentirely or to a predetermined extent, so that, when the tool is pulledout of the work piece, for example, no dust or no additional dust leavesthe protective cover and enters the surroundings.

A guard device, the protective cover of which completely encompasses thetool in the axial direction in the resting position, ensures a highlevel of work safety: an operator is effectively protected againstinjury caused by the tool. This also applies for a guard device, in thecase of which the tool retracts completely into the protective coverwhen it exits the work piece. Additionally, such a guard device ensuresgood protection against the release of sanding dust or particles. Thedust rotating with the tool is drawn into the protective cover alongwith the tool retracting into the protective cover.

Advantageously, the protective cover comprises an exit region in whichthe tool partially exits the protective cover during operation, wherebythe protective cover has a glide shoe in the exit region, and the dustremoval tube is permanently interconnected with the glide shoe. Theglide shoe guides the protective cover along the work piece and holdsthe dust removal tube at a constant distance from the work piece. Inthis fashion, the mouth of the dust removal tube can be positioned insuch a way that it points in the direction of flight of the particles.

If the glide shoe constricts the cross section of the exit region in theregion of the dust removal tube, it is more difficult for air to escapeout of the protective cover. Excess pressure forms inside the protectivecover that presses the air containing particles or dust toward the dustremoval tube.

Advantageously, an air inlet opening remains in the protective cover orbetween the protective cover and the work piece, the size of which isindependent of the depth of penetration of the tool in the work piece.In this fashion, a constant flow of air—that is independent of the depthof penetration of the tool in the work piece—from the air inlet openinginto a dust removal tube, and, therefore, constant dust removal, is madepossible.

When the air inlet opening is located opposite from the dust removaltube relative to the tool, an air stream directed toward the dustremoval tube is obtained that facilitates entry of dust into the dustremoval tube.

The blow-off effect of the sanding dust is further improved by means ofa damping plate located inside the protective cover, since the airwhirled by the rotating sanding disk backs up there, and the air streamis directed out to the dust removal tube. The damping plate can belocated on the side opposite from the dust removal tube and beintegrally molded on the protective cover, for example.

A further advantage is achieved in that the protective cover comprises awindow that provides an operator with a view of the tool and, inparticular, on the side of the tool closest to a work piece. Aparticularly easy and good control of the tool position in the workpiece is therefore possible.

Advantageously, the protective cover comprises an observation slit. Itcan be formed by means of an opening in the protective cover, forexample, or by means of a slant in part of the protective cover. Theobservation slit directed toward the narrow side of the sanding diskensures a more controlled handling of the angle grinder with theprotective cover, mainly for exact placement of the sanding disk inmortar joints. Visual control of the tool is particularly enhanced bymeans of the window in combination with an observation slit. The airinlet opening can be used as an observation slit. The air drawn inthrough the observation slit causes turbulence that essentially keepsthe window free from dust. When the dust is removed from the oppositeside of the window, e.g., by a dust removal tube located there, thewindow remains essentially free from dust as a result of the airturbulence.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages result from the following description of thedrawings. An exemplary embodiment of the invention is presented in thedrawings. The drawings, the description, and the claims contain numerousfeatures in combination. One skilled in the art will advantageouslyconsider them individually as well and combine them into reasonablefurther combinations.

FIG. 1 is a top view of a power tool having a guard device according tothe invention, in the working position,

FIG. 2 is a view of the power tool in FIG. 1 from above,

FIG. 3 is a view of the power tool in FIG. 1 from the opposite side,

FIG. 4 is the view according to FIG. 3 rotated by 90° around thevertical axis,

FIG. 5 is the view according to FIG. 1 in the resting position,

FIG. 6 is the view according to FIG. 5 from the opposite side,

FIG. 7 is the side view of a further exemplary embodiment of a powertool having a guard device according to the invention, in the restingposition,

FIG. 8 is the view according to FIG. 7 from the opposite side,

FIG. 9 is the view according to FIG. 8 rotated 90° around thelongitudinal axis,

FIG. 10 is the view according to FIG. 7 in the working position,

FIG. 11 is a detailed view of the dust removal tube acoding to FIGS. 7and 10,

FIG. 12 is a spatial representation according to FIG. 1,

FIG. 13 is a spatial view from below according to FIGS. 1 and 2,

FIG. 14 is a view of the adjustable stop for limiting the depth of cut,

FIG. 15 is a detailed view of the depth-of-cut stop,

FIG. 16 shows a section of the pivoted cover plate,

FIG. 17 is a bottom view of the angle grinder protective cover accordingto FIG. 1,

FIG. 18 shows a side shell of the protective cover as seen from theoutside,

FIG. 19 shows the housing shell according to FIG. 18 as seen from theinside,

FIG. 20 is a spatial representation of the anterior region of thesanding machine comprising dust removal tube extending at a slantrelative to the sanding tool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is the side view of an angle grinder 20, the motor housing 22 ofwhich extends substantially upward at a right angle and contains anot-shown motor.

As viewed downward at a right angle, a gearbox housing 24 adjoins themotor housing 22, the drive shaft 26 (FIG. 13) of which said gearboxhousing extends at a right angle to the plane of the drawing and carriesa tool on its exposed end. The tool is a sanding disk 28. It rotates inthe direction of rotation 29 in a clockwise direction and plunges into awork piece 30, in which it cuts a groove 32 coming from the right.

As shown on the left side, a sliding button 34 of an on-and-off switchis attached to the motor housing 22.

A guard device 33 is fastened to the angle grinder 20. It comprises afastening device and a protective cover 40. The fastening device isdesigned as a swivelling arm 38. The swivelling arm 38 is fastened via awell-fitting mounting opening 36 (FIG. 18) to a cylindrically designed,axial extension of the gearbox housing 24, i.e., the neck 25. Theswivelling arm 38, in turn, is fastened to the protective cover 40 andis capable of being swivelled upward and downward around a center ofrotation 42. The swivelling arm 38 and the protective cover 40 arereliably guided in opposition to each other by means of a guide bolt 46seated on the protective cover 40 in a guide slot 44 of the swivellingarm 38. As shown on the left side, the swivelling arm 38 carries a knob48, by way of which the angle grinder 20 with the protective cover 40can be guided on a work piece 30. The knob 48 is also grasped tomanually adjust the depth of cut, whereby the swivelling arm 38 can beadjusted upward and downward. The protective cover 40 is seated on thework piece 30 with a guide means, i.e., a rail 50 designed in the shapeof a runner, located on its bottom side. The guide means ensures thatthe protective cover 40 remains perpendicular to the surface of the workpiece.

As shown on the bottom left, the protective cover 40 carries a dustremoval tube 52 directly adjacent to the rail 50. Dust created duringsanding is removed through said dust removal tube, e.g., via an insertedtube piece and a dust suctioning device attached thereto. The dustremoval tube 52 is situated at a 45° angle relative to the axis ofrotation of the sanding disk.

As shown on the bottom right, the protective cover 40 is angled at aslant in the upward direction, so that an observation opening 54 isformed, through which the tool operator can control the engagement ofthe sanding disk 28 in the work piece 30 and/or the groove 32. As shownat the top right, a handle 56 projects out of the protective cover 40 atan angle, by way of which the unit comprising angle grinder 20 andprotective cover 40 can be comfortably guided along the work piece 30.

A spring mechanism is located between the swivelling arm 38 and theprotective cover 40 at the center of rotation 42. The spring mechanismcomprises a preloaded leg spring 58 that tries to press the swivellingarm 38 upward. As a result, the angle grinder 20 must be moved relativeto the protective cover 40 according to FIG. 1 in a counterclockwisedirection against the spring force of the leg spring 58 in order toreach its working position in which the sanding disk 28 protrudesdownward out of the pass-through slot 73 (FIG. 17) and/or past the rail50 so that it can penetrate the work piece 30.

If the angle grinder 20 with the protective cover 40 is lifted off ofthe work piece 30, the leg spring 58 pulls the protective cover 40downward relative to the swivelling arm 38, so that the sanding disk 28disappears completely inside the protective cover 40.

The usual method of working with the angle grinder 20 is in theadvancing direction 57, so that the work piece 30 and the direction ofrotation 29 are opposite to the direction of rotation 29 of the sandingdisk 28.

The view from the top shown in FIG. 2 shows the slanted arrangement ofthe handle 56 on the protective cover 40, and the slanted extension ofthe dust removal tube 52. Moreover, the neck 25 of the gearbox housing24 is shown, which said neck engages in the mounting opening 36 of theswivelling arm 38.

FIG. 3 shows the angle grinder 20 with protective cover 40 according toFIG. 1 from the opposite side, also in the working position, with thesanding disk 28 protruding far downward. A guide rule 60 is shown inFIG. 3, on which the knob 48 is guided and which can be locked inposition by rotating it around its longitudinal axis. Furthermore, adepth-of-cut stop 62 is shown below the knob 48, which said depth-of-cutstop is also capable of being displaced in the guide rule 60 and whichis capable of being locked in position with positive engagement inpreselected, stepped positions by the press of a button. Thedepth-of-cut stop 62 is captively secured on the guide rule 60 (FIGS.14, 15).

The guard device 33 comprises two units capable of being moved oppositeto one another, i.e., the protective cover 40 and a pivoted cover plate64. The pivoted cover plate 64 is located on the opposite side of theswivelling arm 38 and is intended to cover the sanding disk 68. Thepivoted cover plate 64 is capable of being swivelled together with theprotective cover 40 around the center of rotation 42. To replace thesanding disk 28, the pivoted cover plate 64 is swivelled toward theupper left—as viewed in this drawing—from the operating position into atool replacement position. In this outwardly swivelled tool replacementposition, the exposed end of the driven shaft 26 and/or the retainingnut 27 (FIG. 13) are easily accessible, so that, after the retaining nut27 is loosened, the sanding disk 28 can be removed in the axialdirection out of the plane of the drawing.

In its lower region, the pivoted cover plate 64 comprises a window 66 ina rectangular opening. Located between the window 66 and the rail 50 isa lateral air inlet opening 68 through which air can pass that replacesthe air blown out by the rotating sanding disk 28 to remove sandingdust. Relative to the sanding disk 28, the air inlet opening 68 islocated opposite from the dust removal tube 52. In a state lying on theflat work piece 30 in the operating position, the air inlet opening 68has a size that does not depend on the depth of penetration of thesanding disk 68 in the work piece 30, since the rail 50—which, togetherwith the protective cover 40, borders the air inlet opening 68—alwayslies flat on the work piece 30 independent of the depth of penetrationof the sanding disk 28 in the work piece 30.

The window 66 is inserted in frame segments 70 fastened to the pivotedcover plate 64, and it engages with the pivoted cover plate 64 incaptive fashion with a snap-in tongue 72 extending above it.

FIG. 4 shows a side view, rotated by 90°, of the angle grinder 20according to FIG. 3, whereby, in contrast to the preceding figures, thedesign of the guide rule 60 comprising a central slot 61—for swivellingthe knob 48 vertically and/or for moving the depth-of-cut stop 62 withits push button 63—is shown. The sanding disk 28 is also shownpenetrating the groove 32, which said groove is designed as a mortarjoint. The rest of the details explained hereinabove are labelled withreference numerals but will not be explained once more.

FIG. 5 shows the angle grinder 20 according to FIG. 1 with theprotective cover 40 in the resting position, in which the sanding disk28 has disappeared inside the protective cover 40, because theswivelling arm 38 has been moved upward relative to the protective cover40. This is made particularly clear when the relative position of theguide bolt 46 to the guide slot 44 according to FIG. 5 is compared withsaid relative position of the guide bolt to the guide slot in FIG. 1.

FIG. 6 shows how the sanding disk 28—located behind the rail 50—ispositioned within the contour of the protective cover 40.

In FIGS. 5 and 6, the resting position of the protective cover 40 isrecognizable by the fact that the knob 48—as viewed here—is seatedagainst the upper stop of the guide rule 60.

FIGS. 7 and 8 show an exemplary embodiment that is slightly modified ascompared with FIGS. 1 through 6, comprising a guard device 133, in thecase of which a dust removal tube 152 projecting out of the protectivecover 140 at a right angle is provided, which said dust removal tube isprovided for suctioning purposes using a separate vacuum cleaner.Moreover, an elongated, stem-like handle 156 is attached directly to theangle grinder 120 in order to make two-handed operation of the anglegrinder 120 possible, whereby one hand can grasp the handle 156, and theother hand can grasp the motor housing 122. Moreover, the swivelling arm138 is provided with a knurled nut 148 instead of a knob, with whichsaid knurled nut the preselected depth of cut can be adjusted. Locatedon the underside of the protective cover 140 is a rail 150 for guidanceon a work piece 30 shown in FIG. 10.

FIG. 8 shows the view according to FIG. 7 from the opposite side,whereby, in contrast to FIG. 3 of the first exemplary embodiment, thewindow 166 is capable of being secured by means of a knurled nut.

FIGS. 7 and 8 show the angle grinder 120 with the protective cover 140in the resting position, i.e., with the sanding disk 28 drawn into theprotective cover 140, while FIGS. 9 and 10 show the same angle grinder120 in the working position, i.e., with the sanding disk 28 protrudingbelow the rail 150.

FIG. 9 clearly shows a collet 123 that clamps a collar of the protectivecover 140 tightly against the neck 125 of the angle grinder 120. Theprotective cover 140 is easy to remove by loosening a hexagon bolt andopening the collet 123 away from the neck 125 of the angle grinder 120if the sanding disk 28 was previously removed. Also shown are theknurled nut 167 for holding the pivoted cover plate 164 in positionagainst the protective cover 140, the knurled nut 148 for setting andreleasing the preselected depth of cut, and the depth-of-cut stopcapable of being adjusted using the knurled nut 162.

FIG. 9 clearly shows the leg spring 158, with which the angle grinder120 is automatically moved relative to the protective cover 140 aroundthe center of rotation 142 into the resting position. Also shown is asuction tube 151 for connection to a vacuum cleaner, with which thesanding dust can be effectively removed.

FIG. 10 shows the angle grinder 120 in the working position, wherebysanding dust is thrown in the direction of rotation 29 of the sandingdisk 28 tangentially from the point where the sanding disk 28 exits thework piece 30 and against the interior wall of the dust removal tube152, and from there, it is capable of being suctioned off easily via thesuction tube.

FIG. 11 shows a detained view of the dust removal tube 152 in itsposition relative to the sanding disk 28. One can see that the radiallyoutermost region of the sanding disk 28 extends into an opening 174 ofthe dust removal tube 152. Part of the dust removal tube 152 thereforepenetrates the planes—imagined to continue endlessly—of the two flatsides of the sanding disk 28. The opening 174 is designed in such afashion that part of the dust removal tube 152 reaches behind thesanding disk 28. The opening 174 is therefore designed in the shape of aslot.

The conveying air stream produced by the sanding disk 28—together withdust particles—meets the bent surface of the part of the dust removaltube 152 that penetrates the planes of the two flat sides of the sandingdisk 28, as indicated by the arrows. The conveying air stream with thesanding dust meeting this impact surface at a high rate of speed isfurther directed into the dust removal tube 152 in such a fashion thatit executes a cyclone-like vortex motion in the dust removal tube. Theconveying air and dust stream set into rotational motion in this fashionhas sufficient kinetic energy to exit the dust removal tube 152 on itsside furthest from the angle grinder 20 under its own power. A vacuumcleaner can be installed downstream for safety reasons, however, toprevent the dust removal tube 152 from becoming blocked in certainworking positions of the angle grinder 120.

FIG. 12 shows a side view of a further exemplary embodiment, the designof which essentially matches that of the angle grinder 20 shown in FIGS.1 through 4. The only differences are that the stem-like handle 56 isscrewed directly onto the gearbox housing 24 of the angle grinder 20,and the knob is missing. The collet 23 and the locking screw that holdthe angle grinder 20 tightly in position relative to the protectivecover 40 are particularly easy to see.

FIG. 13 shows a spatial representation nearly parallel to the sandingdisk 28 from the underside of the protective cover 40. The design of therail 50 with a glide shoe 49 is shown particularly clearly. The rail 50is located in the exit region of the protective cover 40, where part ofthe sanding disk exits the protective cover 40 during operation. Theglide shoe 49 of the rail 50 constricts the cross section of the exitregion of the protective cover 40. This helps the air stream in theprotective cover 40 along in the direction toward the dust removal tube52.

As shown on the left side, a damping plate 76 is located next to thesanding disk 28, which said damping plate extends radially very close tothe periphery of the sanding disk 28 and dampens a movement of aircaused by the rotating sanding disk 28 during sanding. As a result, acertain vacuum is produced inside the protective cover 40, which saidvacuum blows through the dust removal tube 52 and takes any sanding dustpresent along with it.

The collet 23 with the clamping nut for fastening the protective cover40 to the gearbox housing 24 is shown. On the top, the protective cover40 is covered horizontally with the pivoted cover plate 64 made of sheetmetal, attached to which said pivoted cover plate—as shown on the rightside—is a round, projecting swivel grip 65 to be operated using thethumb.

As shown on the left side, an arrow indicating the direction of rotationis stamped in the pivoted cover plate 64 that points to the left in theview shown. This is the intended direction of rotation for swivellingthe pivoted cover plate 64 upward into its release position to removethe sanding disk 28. Additionally, the arrow also indicates thedirection of rotation of the sanding disk 28. The pivoted cover plate 64is swung to the left by approximately 180° around the center of rotation42 so that the sanding disk 28 can be exposed and replaced after theretaining nut 27 is removed.

The frame segments 70 for accommodating the window 66 in thecorresponding opening are also clearly shown.

FIG. 14 shows the guide rule 60 as a fixed part of the protective cover40, relative to which the swivelling arm 38 can be adjusted viaswivelling. The position of the swivelling arm 38 relative to the guiderule 60 can be fixed and/or released using the knurled thumb screw 48 aand/or using the knob 48 shown in FIGS. 1 through 4 by turning themaround their axes.

The push button 63 of the depth-of-cut stop 62 can be engaged in thetoothed rack-like outer contour 59 by way of a mirror-image profile, andit can be disengaged with spring action by pressing on the push button63. If pressure on the push button 63 is released, it automaticallyengages with its mating profile 79 in the toothed rack-like outercontour 59 in the respective position. The depth-of-cut stop 62 can befixed in position at any position along the guide rule 60, so that theswivelling arm 38 with its knurled thumb screw 48 a can only beswivelled up to said stop. With this, a reproducible depth of cut isestablished.

FIG. 15 shows a detained view of the depth-of-cut stop 62 with its pushbutton 63 and a profile carrier 78 made of sheet metal that forms themating profile 79 for engaging in the toothed rack-like outer contour 59of the guide rule 60. A tab 80 is located on each of the opposite sidesof the profile carrier 78, which said tabs fit in the center slot 61 ofthe guide rule 60 for guided engagement. The profile carrier 78 ispenetrated transversely by a guide bolt 82, along which it can be movedtoward the push button 63 and away from said push button. The pushbutton 63 is preloaded elastically by means of a spiral-coiled spring83.

The push button 63 and the profile carrier 78 are securely bracedagainst each other, whereby, in the assembled state, the guide rule 60runs along between the two. The spiral-coil spring 83 with a supportdisk 84 comes to bear at the top against the guide rule 60 and, when thepush button 63 is operated, it moves in an axially spring-loaded fashionrelative to the guide rule 60, so that the profile carrier 78 with itsmating profile 79 can disengage from the outer contour 59 of the guiderule 60.

FIG. 16 shows a section of a spatial representation of the swivel grip65 of the pivoted cover plate 64. It is formed by part of the pivotedcover plate 64. As shown on the left, the pivoted cover plate 64comprises a tab 86 bent outwardly upward, through which a flexibletongue 88 of an L-shaped leaf spring 89 extends, which said leaf springis interconnected flatly with the rail 50, i.e., they are rivetedtogether in this case.

One of the frame segments 70 into which the window 66 can be inserted isshown at the top.

An opening 90 in the pivoted cover plate 64 is

shown on the right side, which said opening snaps into place over adetent lobe 92 that extends out of the adjacent side wall of theprotective cover 40. By swiveling the pivoted cover plate 64 using theswivel grip 65 to the right as viewed here, the tab 86 can glide overthe flexible tongue 88, and the opening 90 can overcome the detent lobe92, so that the pivoted cover plate 64 can then be rotated around thecenter of rotation 42 (FIG. 13) with minimal force.

FIG. 17 shows an underside view of the protective cover 40 with the topview of the runner-like rail 50. Its surface forms a pass-through slot73 through which the not-shown sanding disk 28 can enter and exit.

Shown at the bottom is the collet 23 with the pass-through opening 36for accommodating the neck 25 of the angle grinder 20 (FIG. 1). The legspring 58 is shown at the outer left, which said leg spring tries toswivel the swivelling arm 38 around the center of rotation 42, while thedust removal tube 52 projects in the lower right-hand side of thedrawing. The dust removal tube 52 tapers toward its mouth pointingtoward the sanding disk 28. As a result, the conveying air streamproduced by the sanding disk 28 flows rapidly in the axial direction ofthe dust removal tube 52 through the constriction in the mouth of thedust removal tube 52. It therefore leaves the inside of the protectivecover 40 at great speed, whereby it executes the rotational motiondescribed with FIG. 11. Due to the widening of the dust removal tube inthe direction away from the protective cover 40, the air stream developsa suction effect due to its rotation, which said suction effect helpsthe air to exit the protective cover and enter the dust removal tube 52.

The protective cover 40 is covered on the top by the pivoted cover plate64, the frame segments 70 of which project upwardly and hold the window66. Additionally, the tab 86 is shown on the pivoted cover plate 64 atthe top right.

FIG. 18 shows a detained view of the stationary, shell-like side part 96of the protective cover 40, to which the welded-on guide rule 60 isattached as shown on the right.

The runner-like region of the rail 50 and the dust removal tube 52 canbe seen in the upper right. Shown particularly clearly here is thearrangement of the suction tube in the outermost corner of theprotective cover 40, at the site of origination of the sanding dust whenthe angle grinder 20 is used, through which said suction tube anysanding dust created moves by means of the high natural speed impartedby the sanding disk 28 in conjunction with the blast air stream producedby the sanding disk 28 itself.

Located approximately in the middle of the side part 96 is thepass-through opening 36, through which the neck 25 of the angle grinder20 extends. The pass-through opening 36 is a slot that allows the anglegrinder 20 and/or the neck 25 to swivel up and down relative to theprotective cover 40 until the maximum depth of cut is reached.

FIG. 19 shows the side part 96 as viewed from the inside, whereby therail 50, the dust removal tube 52, and the guide rule 60 are shownparticularly clearly. Moreover, the damper plate 76 and the observationopening 54 are shown on the outermost side of the side part 96.

FIG. 20 is a side view of the protective cover 40 showing a section inthe region of the gearbox housing 24 of the angle grinder 20. Also shownclearly is the knob 48 for guiding the protective cover 40 and/or foradjusting a preselected depth of cut and the depth-of-cut stop 62.

Also shown is the dust removal tube 52, in the circumferential contourof which the sanding disk 28 passes through the opening 74 with itsradially outermost region.

Reference numerals

-   20 Angle grinder-   22 Motor housing-   23 Collet-   24 Gearbox housing-   25 Neck-   26 Drive shaft-   27 Retaining nut-   28 Sanding disk-   29 Direction of rotation-   30 Work piece-   32 Groove-   33 Guard device-   34 Sliding button-   36 Mounting opening-   38 Swivelling arm-   40 Protective cover-   42 Center of rotation-   44 Guide slot-   46 Guide bolt-   48 Knob-   48 a Knurled thumb screw-   49 Glide shoe-   50 Rail-   52 Dust removal tube-   54 Observation opening-   56 Handle-   57 Advancing direction-   58 Leg spring-   59 Outer contour-   60 Guide rule-   61 Slot-   62 Depth-of-cut stop-   63 Push button-   64 Pivoted cover plate-   65 Swivel grip-   66 Window-   68 Air inlet opening-   70 Frame segment-   72 Snap-in tongue-   73 Pass-through slot-   74 Opening-   76 Damping plate-   78 Profile carrier-   79 Mating profile-   80 Tab-   82 Guide bolt-   83 Spiral-coiled spring-   84 Support disk-   86 Tab-   88 Flexible tongue-   90 Recess-   92 Detent lobe-   96 Side part-   120 Angle grinder-   122 Motor housing-   123 Collet-   125 Neck-   133 Guard device-   138 Swivelling arm-   140 Protective cover-   142 Center of rotation-   148 Knurled nut-   150 Rail-   152 Dust removal tube-   156 Handle-   158 Leg spring-   162 Knurled nut-   164 Pivoted cover plate-   166 Window-   167 Knurled nut-   174 Opening

1. A guard device (33) for a power tool, comprising; a protective cover(40) configured to at least partially encompass a disk-shaped, rotatingtool having two flat sides defined by two corresponding planes, and anaxis of rotation; a dust removal tube (52) having a longitudinal axislocated at an angle of up to 80 degrees to said axis of rotation of saidrotating tool; wherein said dust removal tube (52) extends along saidlongitudinal axis pass behind said rotating tool, penetratingtransversely both planes of said two flat sides such that a radiallyoutermost region of the rotating tool extends into an opening (74,174)of the dust removal tube in a form of a slot transverse to saidlongitudinal axis, so that dust drawn off a work piece is set into arotational motion in the dust removal tube.
 2. The guard device (33)according to claim 1, wherein the dust removal tube (52) includes amouth, and wherein the dust removal tube (52) tapers toward the mouthpointing toward the work piece.
 3. The guard device (33) according toclaim 1, further comprising a fastening device to fasten the protectivecover (40) to the power tool, whereby the dust removal tube (52) ismoveably supported relative to the fastening device.
 4. The guard device(33) according to claim 1, wherein the dust removal tube (52) isfastened to the protective cover (40).
 5. The guard device (33)according to claim 1, wherein the protective cover (40) encompasses therotating tool together with a flat work piece (30) to an extent thatdoes not depend on the depth of penetration of the rotating tool in theflat work piece (30) when the protective cover is lying on the flat workpiece in an operating position.
 6. The guard device (33) according toclaim 1, wherein the protective cover (40) comprises an exit region inwhich the rotating tool partially exits the protective cover (40) duringoperation, and the protective cover (40) comprises a glide shoe (49) inthe exit region, whereby the dust removal tube (52) is permanentlyinterconnected with the glide shoe (49).
 7. The guard device (33)according to claim 6, wherein the glide shoe (49) narrows the crosssection of the exit region in a region of the dust removal tube (52). 8.The guard device (33) according to claim 1, wherein the protective cover(40) comprises an air inlet opening (68) when the protective cover islying on a flat work piece in an operating position, wherein a size ofthe air inlet opening is independent of the depth of penetration of therotating tool in the work piece (30).
 9. The guard device (33) accordingto claim 8, wherein the air inlet opening (68) is located opposite fromthe dust removal tube (52) relative to the rotating tool.
 10. The guarddevice (33) according to claim 1, further comprising a damping plate(76) secured to the protective cover (40).
 11. An angle grindercomprising; a guard device (33) including a protective cover (40)configured to at least partially encompass a disk-shaped, rotating toolhaving two flat sides defined by two corresponding planes, and an axisof rotation, said guard device further including a dust removal tube(52) having a longitudinal axis located at an angle of up to 80 degreesto said axis of rotation of said rotating tool; wherein said dustremoval tube (52) extends along said longitudinal axis pass behind saidrotating tool, penetrating transversely both planes of said two flatsides such that a radially outermost region of the rotating tool extendsinto an opening (74, 174) of the dust removal tube in a form of a slottransverse to said longitudinal axis, so that sanding dust drawn off awork piece is set into a rotational motion in the dust removal tube.